1. Field of the Invention
The present invention relates to an image forming method and apparatus which use an expandable material to form an embossed image, and more particularly to an image formation method and image formation apparatus which can easily and simply form a desired embossed image by converting height information on the embossed image to density information which indicates a density of a non-embossed image and controlling an amount of an expandable material which is transferred onto a recording medium according to the converted density information.
2. Description of the Related Art
Conventionally, an image formation apparatus such as a printer or a copy machine which adopts an electrophotographic method or an electrostatic recording method forms flatly an image such as characters, figures, photographs or the like in black and white or full color on a recording medium such as a recording sheet, and the formed image is visually recognized and used as a desired information conveying unit.
Meanwhile, it is demanded in recent years to provide a method which can convey to a third party not only visually flat information by an image formed on a recording medium but also a variety of information by addition of three-dimensional information based on shadows produced by vertical intervals of the image or the touch with fingers.
As a method to add three-dimensional information to the image, there is a method to form the image as a three-dimensional embossed image.
The method of forming an embossed image has been devised in various ways, and a variety of techniques have been proposed.
For example, as a method of producing a pamphlet or the like having an embossed image, there is a method to form an embossed image by printing an ultraviolet-curing type high-viscosity polymer ink into a raised form by a printing technique such as ordinary silk-screening and curing by irradiating ultraviolet rays to form an embossed image, but such a method cannot be easily used by an ordinary office or a public facility.
Japanese Patent Application Laid-Open Publication No. 52-28325 proposes a toner for electrophotography containing a dry expandable agent.
This toner for electrophotography containing a dry expandable agent is a toner which has a conventional toner and the dry expandable agent mixed in powder form and can be used to obtain an embossed image by forming an image and expanding the dry expandable agent by heating.
But, some powder mixture cannot have the toner and the expandable agent mixed uniformly and adequately, the expandable agent not having an adhesive power is often on the interface with paper, and an embossed image having an adequate fixing property cannot be obtained.
Japanese Patent Application Laid-Open Publication No. 7-061047 proposes an information input/output method for forming a projection image by using a toner containing a heat-sensitive expanding agent.
The toner used for the above method is produced by mixing and finely pulverizing a binder resin for a toner, a coloring agent and a heat-sensitive expanding agent. The pulverized toner has the heat-sensitive expanding agent revealed on its surface.
Therefore, the heat-sensitive expanding agent is exposed on the interface between paper and the toner. The adhesion between the toner and the paper is degraded in the same way as the above-described proposition, and the obtained image has a degraded fixing property.
Because the heat-sensitive expanding agent is exposed to the toner surface, the toner surface has a nonuniform electrostatic property. Therefore, the toner has a wide distribution of electrification, and when the toner is used under low-temperature and low-humidity environments or for a long period, the image has fogging or the like, and image quality is degraded.
Besides, because the used toner is produced by an ordinary kneading and pulverizing method, it is considered that the heat-sensitive expanding agent is mostly expanded by heating at the time of kneading and its effect is lost.
As a result, the expanding agent cannot expand sufficiently when thermally fixed only by an ordinary copy machine or the like. It is necessary to additionally pass the output image through an overheating device. It is insufficient in terms of simplicity and easiness.
Therefore, the present applicant has already proposed a novel image forming toner which can be used to easily form an embossed image by a common copy machine or a printer and an image formation apparatus using the above image forming toner (Japanese Patent Application Laid-Open Publication No. 2000-131875 and Japanese Patent Application Laid-Open Publication No. 2001-134006).
The image formation apparatus according to Japanese Patent Application Laid-Open Publication No. 2000-131875 is configured in such a way that the toner contains at least a binder resin and an expanding agent, the toner does not substantially have the expanding agent exposed to the toner surface, and the expanding agent contained in the toner is expanded by a fixing unit to form an embossed image on a recording medium. Thus, by using the toner containing the binder resin and the expanding agent, an embossed image can be formed on a recording medium.
The image formation apparatus according to Japanese Patent Application Laid-Open Publication No. 2001-134006 uses a toner which contains at least a binder resin and an expanding agent. To fix the toner image formed with the toner on a recording medium by a fixing unit, the expanding agent contained in the toner is expanded by the fixing unit to form the embossed image on the recording medium, and the fixed toner image has an image structure in which the expanding agent has at least two layers of expanded gas bubble. After the thermal fixing processing, an embossed image having adequate height and durability can be formed.
Japanese Patent Application Laid-Open Publication No. 2000-131875 and Japanese Patent Application Laid-Open Publication No. 2001-134006 are effective as techniques to realize an embossed image. But, they do not disclose a method of designating height information to actually give ups and downs to a print such as a map, graphics, a photograph image or the like and a method of forming an embossed image from image data.
Under the circumstances described above, the present invention provides an embossed image formation apparatus and embossed image information method which can easily form an embossed image desired by the user.
The present invention has been made in view of the above circumstances and an aspect of the present invention is an image formation method for forming an image containing an embossed portion of an expandable material on a recording medium, comprising: converting height information about an embossed image which is the image of the embossed portion to same density information as one used to indicate a density of a non-embossed image which is not raised; and controlling an amount of the expandable material formed on the recording medium according to the converted density information.
Another aspect of the present invention is an image formation method for forming an image containing an embossed portion of an expandable material on a recording medium, comprising: converting height information about an embossed image which is the image of the embossed portion to same density information as one used to indicate a density of a non-embossed image which is not raised; and sending the converted density information to an image formation apparatus which controls an amount of the expandable material formed on the recording medium according to the density information.
Still another aspect of the present invention is an image formation apparatus for forming an image containing an embossed portion of an expandable material on a recording medium, comprising: a conversion unit which converts height information about an embossed image which is the image of the embossed portion to same density information as one used to indicate a density of a non-embossed image which is not raised; and a control unit which controls an amount of the expandable material formed on the recording medium according to the density information converted by the conversion unit.
According to the present invention, it is possible to form an embossed image, whose height on a recording medium is controlled, by an ordinary electrophotographic type copy machine, a small printer or the like.
As used in the specification and claims herein, the word xe2x80x9cembossed imagexe2x80x9d refers to an image having a three-dimensional appearance.